1. Field of the Invention
The present invention relates to a seatbelt device configured to protect an occupant in a vehicle, and more particularly to a seatbelt device in which a seatbelt retractor is incorporated into a seat back of a reclining seat.
2. Description of the Related Art
A seatbelt device mounted on a vehicle is configured to protect an occupant seated on a seat when the vehicle crashes or the like by restraining the occupant with a seatbelt drawn out of a seatbelt retractor. The seatbelt retractor includes an acceleration sensor configured to detect acceleration that is larger than a predetermined value and applied in a horizontal direction when the vehicle crashes or the like, and a lock mechanism for the seatbelt configured to prevent the seatbelt from being drawn out when the lock mechanism is actuated. Examples of an inertial element for use in the acceleration sensor include a ball and a self-standing inertial element.
In the case where a seatbelt retractor having an acceleration sensor of this type is provided in a seat back of a reclining seat, acceleration may not be detected adequately because the attitude of the seatbelt retractor is varied in accordance with the reclining angle (inclination angle) of the seat back. Thus, there are known seatbelt devices provided with an acceleration sensor capable of adequately detecting acceleration irrespective of the reclining angle of the seat back (see Japanese Patent Application Laid-open No. 2000-79867, Japanese Patent Application Laid-open No. 2000-52921, and Japanese Patent Application Laid-open No. H11-326362, for example).
In the seatbelt devices described in Japanese Patent Application Laid-open No. 2000-79867, Japanese Patent Application Laid-open No. 2000-52921, and Japanese Patent Application Laid-open No. H11-326362, a cable advancing/retracting mechanism, configured to advance and retract a cable by a length corresponding to the inclination angle of a seat back, is disposed at a coupling portion where a seat back support arm provided to project from a seat cushion and a reclining rotary shaft are coupled to each other. A sensor reference line of an acceleration sensor is controlled by a cable extending between the cable advancing/retracting mechanism and a seatbelt retractor such that the sensor reference line is always directed in the vertical direction to enable adequate detection of acceleration when the seat back is tilted forward and/or rearward.
The attachment angle of the seatbelt retractor to the seat back in the vehicle width direction (the left-right direction of the vehicle) is different in accordance with the vehicle model, the vehicle seat specifications, or the like in order to ensure that the seatbelt is drawn out smoothly. In a seatbelt device described in Japanese Patent Application Laid-open No. H11-326362, the attitude of an acceleration sensor is adjustable to the vertical direction in correspondence with variations in attachment angle not only in the front-back direction of the vehicle but also in the vehicle width direction.